Apparatus for straightening metallic extrusions



May 10, 1960 E. J. DE RIDDER ETAL APPARATUS FOR STRAIGHTENING METALLICEXTRUSIONS Original Filed July 12, 1955 9 Sheets-Sheet 1 Fig. l

IN VEN TOR. m} .mbxenauu ATTORNEY Mair 10, 1960 E. J. DE RIDDER ETAL2,936,018

APPARATUS FOR STRAIGHTENING METALLIC EXTRUSIONS 9 Sheets-Sheet 2Original Filed July 12, 1955 N A A v 3 W 3:5

i 1 A a ATTORNEY y 1960 E. J. DE RIDDER ETAL 2,936,018

APPARATUS FOR STRAIGHTENING METALLIC EXTRUSIONS 9 Sheets-Sheet 3 llimwNN Original Filed July 12, 1955 TO 5 BY My s 1111 4/. ATTORNEY///X///// 4 N H %A V D u n by $3 M A 1 2 52 w u. A.... m m W llllllllllII lllllll W T w mm W .WW 7 III NW h \\N% V V m M a I q x m W 7 MN W lan mm. lhwmmxi I 1 7 Ill Hiram i 4 I W lags h n Q W Q M n u u May 10,1960 E. J. DE RIDDER ET AL 2,936,018

APPARATUS FOR STRAIGHTENING METALLIC EXTRUSIONS Original Filed July 12,1955 9 Sheets-Sheet 4 Fig.5

INV NTO his 1 M,

ATTORNEY y 1960 E. J. DE RIDDER ETAL 2,936,018

APPARATUS FOR STRAIGHTENING METALLIC EXTRUSIONS Original Filed July 12,1955 9 Sheets-Sheet 5 INVEINPTOR. .fllide".- f w ATTORNEY y 6 E. J. DERIDDER ETAL 2,936,018

APPARATUS FOR STRAIGHTENING METALLIC EXTRUSIONS Original Filed July 12,1955 9 Sheets-Sheet 6 ATTORNEY y 1960 E. 'J. DE RIDDER ETAL 2,936,018

APPARATUS FOR STRAIGHTENING METALLIC EXTRUSIONS Original Filed July 12,1955 Fig. 14- I a 9 Sheets-Sheet '7 ATTORNEY May 10, 1960 E. J. DERIDDER ET AL 2,936,018

APPARATUS FOR STRAIGHTENING METALLIC EXTRUSIONS Original Filed July 12,1955 9 Sheets-Sheet 8 F:.g.l5

INVENTORS M 44 im qgg zw ATTORNEY May 10, 1960 E. J. DE RIDDER ETAL2,936,018

APPARATUS FOR STRAIGHTENING METALLIC EXTRUSIONS Original Filed July 12,1955 I 9 Sheets-Sheet 9 1 H l n n n :1

IN VEN TORS W 92 My 27 L6 ATTORNEY APPARATUS FOR STRAIGHTENING METALLICEXTRUSIONS Ernst J. De Ridder and Kurt F. Glaser, Richmond, Va.,.assignors to Reynolds Metals Company, Richmond, Va., a corporation ofDelaware Continuation of application Serial No.

1955. This application August 3, 831,431

521,557, July 12, 1959, Serial No.

F 18 Claims. (Cl. 153-32) The present invention relates to a method andapparatus for producing untapered and/r tapered extrusions of many shapeconfigurations straightened to very closev tolerances in one or severaldraw operations.

This application is a continuation of application Serial No. 211,557,filed July 12, 1955 and now abandoned.

To straighten an untapered extrusion by drawing it through a draw diehas been common practice for many years. In a steel disc an opening isout which corresponds very correctly to the cross sectionof theextrusion and the shape is pulled through this die for straighteningpurposes. a

. Thismethod cannot be used if the extrusion is tapered having a thickwall thickness at one end and a thin one at the opposite end. It alsocannot be used on wide extrusions having thin wall thicknesses :andcomplex shape configurations since such rigid draw dies to not provideflexibility for variations. in wall thicknesses caused by toler anceswhich are inevitable in the extrusion process. -A characteristic of ourmethod and apparatus is that each extrusion is longitudinally, and ifnecessary, repeatedly drawn through a specially formed hydraulicstraightening die, in which movable die parts are mounted for varyingthe die opening according to wall thickness variations of the extrusion.7

- The apparatus and general method will be described with reference tothe accompanying drawings, in which:

Figure 1 is a sectional view of a hydraulic die embodying the invention,for straightening a simple rectangular extrusion;

Figure 2 is a sectional view of a hydraulic die of the invention forstraightening an extrusion in the form of a T section;

Figure 3 is a sectional view of a hydraulic die of the invention forstraightening a wide integrally stiffened extrusion;

Figure 4 is a sectional view illustrating a modification of thehydraulic die for the extrusion shown in Figure 3; Figure 5 is a crosssection taken on line 5- -5 of Figure 4; I

Figure dis a schematic fragmentary perspective view showing a splittubular extrusion set up -in a break-press, diagrammatically shown, forthe first step of preliminary flattening of an integrallystiffened'extrusion;-

Figures 7 to 11 inclusive are diagrammatic views showing the fivepressure strokes and four position changes employed in the preliminaryflattening of theextrusion of. Figure 6;

Figure 12 is a plan view of our hydraulic die for straightening anintegrally stiffened extrusion, and embodying the movable core members,the upper pressure shoe not being shown; Figure 13 is a front elevation,partly broken away, showing he structure of Figure 12, a stiffened sheetundergoing straightening being shown, partly in dot and dash line at thetop of the figure;

Figure 14 is a vertical section taken onthe line 14-14 of Figure 12;

Figure 15 is a plan view of one of the steel cores;

Figure 17 is a view in elevation showing the side of a steel core in thecenter or inner areas of our hydraulic die;

Figure 18 is a view similar to Figure 17 showing the,

the form, of steel core adapted for end positions of our hydraulic die;

Figure 19 is a plan view, partly broken away, showing an end area of ourhydraulic die adapted for supporting;v

elements of T-shape; I

Figure 20. is a view in front elevation of the structure shown in Figure19, part of a stiffened sheet with T-,

stifiening members being shown in position, and partly by dot and dashline;

Figure 21 is an end elevation, partly in dot and dash lines showing thestructure of Figures 19 and 20, with overhead pressure shoe member inposition;

Figure 22 is a longitudinal vertical section taken on the line 22.-22,Figure 19, with a stiliened sheet, shown in dotted lines in position;

- Figure 23 is an enlarged view in elevation partly in Section, showingmembers 11, 17, 18 and 19, the latter be-' ing in section;

Figure 24 is a schematic sectional view showing the mounting of theframe which holds all of the'die elements, including the uppermostpressure head, for movement in inclined positions relatively to thestiffened sheet with the effect that the draw bench in any stretch ofthe planar element of the sheet will correspondingly stretch theheadedstiffening elements; 7 V

Figure 25 is a schematic view of adou'ble draw bench; and

Figure 26 is a schematic view of a double acting single draw bench.

Referring to the drawings, Figures 1-5, illustrate suitable apparatusenibodying the present invention, and de signed for straighteningseveral types of metallic extru- SIOHS.

In Figure 1, a hydraulic die'for straightening a simple rectangularextrusion is shown. This die comprises a main frame 33 which also servesas the upper die part. Bolted within frame 33 and at the bottom thereofis a cylinder block 9. Block 9bears a cylinder in which is disposed amovable piston 11 having at its upper end the lower die part 11a. A port27 is provided for the admission of hydraulic fluid to the cylinder. Therectangular metallic extrusion to be straightened by the die of Figure 1is shown at 5.

Referring to Figure 2, there is shown a hydraulic die for straighteningan extrusion in the form of a T section, In this die, cylinder block 9bolted to the main frame 33 contains two cylinders, each bearing apiston 11. Each of. pistons 11 provides at its upper end an angularlower die part 11b adapted to abut the two inner intersect ng surfaceson one side of the T section 5. A suitable by draulic system admitshydraulic fluid to the cylinders,

The hydraulic die of Figure 3 is designed for straightening a wideintegrally stiffened extrusion. Here again, a frame 33 forming an upperdie part has bolted therein a cylinder block 9. Cylinders are providedin block 9 for pistons 11 hearing the lower die pieces or cores 16, \andalso for pistons 12 which provide pressure heads 22 for supporting theleg portions of the extrusion. The two pairs of pistons are operated byhydraulic system 27.

Referring to Figures 4 and'5, a modification of the hydraulic die ofFigure 3 is shown, particularly adapted for straightening extrusion 5along its baseline 5x. Here, the movable die parts 16 carried by pistons11 press against the upper surface of therextrusion, the latter beingsupported on two base portions 33x, which are vertically Patented May10,, 19.60

Figure 16 is an end view of the core shown in Figure:

3 immovable. These latter base portions, however, may slide laterally ofthe direction of draw through the die, due to the dovetail constructionat 32. Cylinder blocks 9 and 9x, bolted together by bolts 28, areprovided respectively for the piston members 11 and '12. Two independenthydraulic systems 27 and 27x operate the pistons.

Referring to Figures 6ll, a method of preliminarily flattening theintegrally stiffened extrusion of the type shown in Figures 35 isillustrated. This method employs a break-press (Figure 6), which is aslong as the length of the extrusion. This press comprises two movablesections 1 and 2, which are adapted to engage the legs of the extrusionas shown in Figures 7-11. Fixed to the upper member 4 of the press is astrip of rubber indicated at 4a. The extrusion 4 is placed in the pressas shown in Figure 6, and is straightened in a succession of steps asindicated'in Figures 7-11.

Referring to Figures 12, 13 and 14, there is provided what may be termeda cylinder block formed by a base member 6, a vertical wall member 7, anopposed and spaced vertical wall member 8, and an internal block 9,bolted together by the screws or bolts The internal walls of members 7,8 and 9 are shaped so as to provide a set of cylinders to receivepistons 11 for acting upon the steel cores later to be described, andintermediate and smaller cylinders which receive pistons 12 which actupon pressure heads '13 for the stiffening legs of the extrusion. InFigure 13 one of the extrusions is shown in dot and dash lines at 14,and the ends of the stiffening legs 15 are of the bulb type.

Each steel core is preferably formed with a wall which tapers at bothsides of a flattened apex, and in Figures 15 and 16 the steel core isindicated at 16, and its contact apex at 16x. Depending from the corehead is a rounded shank 17 having a convex base at 18.

As shown in Figure 13, the convex base of each steel topscorrespondingly formed as indicated at 25, left-hand end of Figure 13,or 26, right-hand end of Figure 22. In such cases, the steel cores maybe somewhat modified as shown in Figure 18 at 16xx.

For admitting hydraulic pressures to each of the pistons 11 for theappropriate steel cores, the die wall assembly is formed with suitableports leading to the base of each cylinder which encloses a piston 11,one of said ports being shown at 27, Figure 13, and similar ports areprovided for the cylinders in which the smaller pistons 12 are actuated,as indicated for example at 29, Figures 13 and 14, and in Figure 22.

Shown in Figure 25 is a schematic view of a double draw bench comprisingdraw benches 34 and 34x. 35 is the hydraulic die which can be tilted,while 36 and 36x are the carriers for extrusion 5. These carriers areconnected by hooks 37 and 37x, respectively, to pulling chains 38 and38x.

Referring to Figure 26, a schematic view of a doubleacting single drawbench 39 is shown. Die 35 is mounted on carrier 40. Extrusion 5 is heldby clamping devices 41 and 41x, only one clamp being in action at atime. Here again, hooks 37 and 37x are provided, connecting the diecarrier to the pulling chain 42, and only one hook is in action at atime.

In the operation of our draw die, a stilfened sheet 5 is placed inposition relatively to the steel cores 16 and pressure head 33, asindicated in the drawings. The front end of the sheet is gripped byclamps (not shown) of draw-bench carriage 36, as illustrated in Figure25, and the stiffened sheet is repeatedly drawn through the die inreversing cycles. By using a draw-bench carriage at opposite ends of thestiffened sheet with the usual draw-bench operating members includingchains, the

core rests in the concave top seat of an annular steel sion isstraightened, the legs and formed ends of the block 19 supported uponthe upper end of a piston 11 for limited transverse movement. As will beseen from Figures 14 and 23, block 19 is formed with a recess whichreceivesthe head 111: of the piston 11. The recess of the block 19 isformed with straight sides to conform A with the sides of the head butis wider at two of its opposed sides to permit limited shift of block 19transversely of the walls 7 and 8 of the assembly.

Between the steel cores 16 are positioned the pressure heads 13 for thelegs of the stiffened extrusion 14. Each pressure head 13 is supportedupon the top of its appropriate piston 12 and may be detachablyconnected to the latter. In the form shown in Figure 13 an apertured lug12x projects into a slot formed in the head 13, a pin 21 holding theelements together. In the form shown in Figure 22 the pressure head isformed with two base recesses which receives two pistons. (See also 30in Figure 19.) Either expedient may be employed, as desired.

It will be seen from Figure 13 that the pressure heads .13 have toprecesses conforming with the bulb tips of the stiffened sheet legs 15,whereas the pressure heads 22 of Figure 22 lack such recesses at theirtops to conform with the T-legs of the stiffened sheet 14x.

In some cases it may be desirable to employ an elongated pressure headfor the stifiened sheet leg intermediate each pair of steel cores, andin Figures 19 and 20, each'elongated pressure head 30 is acted upon bytwo pistons in cylinders indicated by dotted lines at 31, Figures 19 and21.

Inasmuchas the stiffened sheets may, at their sides in some cases, lacklegs of the type shown in Figure 13 or the type shown in Figure 22, butmay have merely the short bar-like leg 23 of Figure 13, or the roundedreinforcing member 24 of Figures 20 and 22, the pressure stiffened sheetmay be drawn back and forth, as will be understood without furtherexplanation.

Since in such operation, with the stiffened sheet 5 being pulled in astraight line, only the top portion of the extrustiffened extrusion willnot be stretched, and this will cause a longitudinal bow in the sheet.To avoid this bow, the die 35 may be set at an adjustable angle to thedirection of draw, as indicated in Figure 24, schematically. In thatfigure, the angle is acute, and beyond that actually required, and forthe purposes of illustration only. By means of such angles, the legs ofthe stiffened sheet are stretched.

By means of hydraulic pressure, the steel cores are pressed against theunderface of the web or top portion of the extrusion, and thereforeagainst the top die piece 33, Figures ,21 and 24., The pressure headswhich act upon the bottoms of the legs may be given a less hydraulicpressure than that exerted by the steel cores, and their action is toprevent lines .of depression in the top of the extrusion which mightoccur between the steel cores in the absence of the said pressure head.

As shown more particularly in Figure 23, the steel cores have a somewhatlesser width than the spacing between the legs of the stifiened sheet,and the base of each steel core is enabled to shift angularly because ofits concave base and the convex seat provided therefor in the steelblock 19, Figure 23. Also the steel block may shift bodily with thesteel core and relatively to the head 11x of the piston 11. Thusirregularities at the under face of the stiffened sheet and in the sidesof the legs thereof will not cause shearing action by the steel cores,but rather they will have an ironing and somewhat kneading action atareas of irregularity, the top portion of the extrusion beingstraightened within close tolerances. v The hydraulic die of ourinvention has special application for stretching tapered extrusions.There is usually a need to stretch extrusions after heat treatment toeliminate non-uniform residual stresses. Tapered extrusions cannot bestretched in the dies of the prior art because heads at the ends of thedie assembly may have their the cross sectional area of the thin end ofthe extrusion isto6' small to permit sufficient stress for stretching"the portions of thicker cross-sectional area. When using the hydraulicdie of our invention, however,'this problem is overcome. While pullingthe extrusion through the die, the local stretching eflect shiftsprogressively along the length of the extrusion. The thick end of thetapered extrusion is pulled first through the die, the hydraulicpressure is decreased according to the decreasing crosssectional area ofthe extrusion, and the danger of overstressing at the thin end of theextrusion is eliminated.

We claim:

1. Apparatus for straightening an elongated sheet-like metal extrusioncomprising: a draw die frame adapted for passage of the extrusiontherethrough; means defining die surfaces carried by said frame forstraightening and smoothing engagement with one of the faces of theextrusion on its said passage, said surfaces being fixed againstmovement normally of the plane of the extrusion during its said passage;a row of die members carried by said frame for movement substantiallynormal to the plane of the extrusion in its said passage through saidframe, said row being disposed transverse to the direction of saidpassage and each of said members having a die surface opposed to saidfixed die surfaces and engageable with the other face of the extrusionfor straightening and smoothing the latter on said passage; fluidpressure means associated with each of said die members for individuallyyieldably urging the latter against the extrusion during said passage;and means for supplying each of said fluid pressure means with fluidunder pressure.

2 The structure defined in claim 1 in which the opposed die surfacesconverge toward each other in the direction of said passage.

3 The structure defined in claim 1 in which the opposed die surfacesdiverge outwardly from each other in opposite directions from a midpointof minimum separation therebetween, whereby the extrusion may be passedin either of said directions through the fame.

4. The structuredefined in claim 1 including means rigidly carried bythe frame and slidably engaging the die members for guiding the latterin their said normal move- :ments while restraining them against anyrocking movements about axes transverse to the direction of the saidpassage, but permitting rocking movements about axes extending'in thedirection of said passage, and including curved interengagingforce-transmitting surfaces between each die member and itscorresponding fluid pressure means for permitting said last-mentionedrocking movement.

5. Apparatus for straightening an elongated sheet-like metalextrusion'having on one of its faces at least one 1substantially-straight integral stiffening rib, the combinationcomprising: a draw die frame adapted for passage of the extrusiontherethrough; means defining die surfaces carried by said frame forstraightening and smoothing engagement with one of the faces of theextrusion on its said passage, said surfaces being fixed againstmovement normally of the plane of the extrusion during its said passage;a row of die members carried by said frame for movement substantiallynormal to the plane of the extrusion in its said passage through saidframe, said row being disposed transverse to the direction of saidpassage and each of said members having a die surface opposed to saidfixed die surfaces and engageable with the other face of the extrusionfor straightening and smoothing the latter in its said passage throughsaid. frame; fluid pressure means associated with each of said diemembers for individually yieldably urging the latter against theextrusion during said passage; and means for supplying each of saidfluid pressure means with fluid under the same pressure.

6. The structure defined in claim 5 including another die member carriedby the frame in spaced relation to the movable die members in the rowand for movement parallel to the latter, said die member having a diesurface engageable with the edgeof' the rib-on the extrusion on passageofthe latter through said frame; another fluid pressure means associatedwith said die member for yieldably urging the latter against the ribedge during said passage; and means for supplying said last-mentionedfluid pressure means with fluid under pressure.

7. The structure defined in claim 5 including another die member carriedby the frame in spaced relation to the movable die members in the rowand for movement parallel to the latter, said die member having a diesurface engageable with the edge of the rib on the extrusion on passageof the latter through said frame; another fluid pressure meansassociated with said die member for yieldably urging the latter againstthe rib edge during said passage; and means for supplying saidlast-mentioned fluid pressure means with fluid under 'a lesser pressurethan that supplied by the supplying means recited in claim 5. I

8. The structure defined in claim 5 in which the die surfaces on the diemembers in the row are adapted to" engage the ribbed face of theextrusion and two of said die members which are adjacent are spacedapart in the row for passage of the extrusion rib therebetween.

9. The structure defined in claim 5 in which the die surfaces on the diemembers in the row are adapted to engage the ribbed face of theextrusion and two of said die members which are adjacent are spacedapart in the row for passage of the extrusion rib therebetween, andincluding another die member carried by the frame between said two diemembers and for movement parallel to the latter, said die member havinga die surface engageable with the edge of the rib on the'extrusion forstraightening and smoothing the latter on passage thereof through theframe; another fluid pressure means associated with said die member foryieldably urging the latter against the rib edge during said passage;and means for supplying said last-mentioned fluid pressure means withfluid under pressure.

1 0'. The structure defined in claim 5 in which the die surfaces on thedie members in the row are adapted to engage the ribbed face of theextrusion and two of said die members which are adjacent are spacedapart in the row for passage of the extrusion rib therebetween, andincluding another die member carried by the frame between said two diemembers and for movement parallel to the latter, said die member havinga die surface engageable with the edge of the rib on the extrusion forstraightening and smoothing the latter on passage thereof through theframe; another fluid pressure means associated with said die member foryieldably urging the latter against the rib edge during said passage;and means for supplying said last-mentioned fluid pressure means withfluid under a lesser pressure than that supplied by the supplying meansrecited in claim 5.

'11. The structure defined in claim 5 including a draw bench, and meansmounting the die frame on said bench for pivotal adjustment about anaxis substantially parallel to the row and disposed between the opposeddie surfaces.

12. Apparatus for straightening an elongated sheetlike metal extrusionhaving on one of its faces a plurality of substantially straight andsubstantially parallel stiffening ribs, the combination comprising: adraw die frame adapted for passage of the extrusion therethrough; meansdefining die surfaces rigidly carried by said frame for straighteningand smoothing engagement with the other face of the extrusion on itssaid passage through said frame; a row of die members carried by saidframe for movement substantially normal to the plane of the extrusion inits said passage through said frame, said row being disposedtransversely of the direction of said passage and each of said membershaving a die surface .opposed to said fixed die surfaces and engageablewith the one face. of the extrusion for straightening and smoothing thelatter in its said passage through said frarnaadjacent die members beingspaced apart in said row for passage of the ribs therebetween;additional die members carried by said frame for movement substantiallyparallel to and disposed between said die members in said row, each ofsaid additional die members having a die surface engageable with theedge of one of the ribs of the extrusion for straightening and smoothingthe latter in its said passage through said frame; fluid pressure meansassociated with each of said die members for individually yieldablyurging the latter against the extrusion during said passage; and meansfor supplying each of said fluid pressure means with fluid underpressure.

13. The structure defined in claim 12 in which the supplying meanssupplies each of the fluid pressure means associated with a member inthe row with fluid under the same pressure, and supplies each of thefluid pressure means associated with the additional members with fluidunder the same; but a lesser, pressure than said firstmentionedpressure.

14. The structure defined in claim 12 including means rigidly carried bythe frame and slidably engaging the die members in therow for guidingthe latter in their said normal movements while restraining them againstany rocking movements about axes transverse to the direction of saidpassage but permitting rocking movements about axes extending inthedirection of said passage, and including curved interengagingforce-transmitting surfaces between each die member in the row and itscorresponding fluid pressure means for permitting said last-mentionedrocking movement.

15. The structure defined in claim 12 including means rigidly carried bythe frame and slidably engaging the die members for guiding the latterin their said normal movements while restraining them against anymovement parallel to the direction of the passage of the extrusionthrough the frame but-permitting movement of each of the die members inthe row transversely of said direction, and interengagedforce-transmitting surfaces between each die member in the row and itscorresponding fluid pressure means for permitting said last-mentionedtransverse movement.

16. Apparatus for straightening an elongated sheetlike metal extrusionhaving on one of its faces a plurality of substantially straight andsubstantially parallel stiffening ribs, the combination comprising: adraw die frame adapted for passage of the extrusion therethrough; meansdefining die surfaces carried by said frame for straightening andsmoothing engagement with the one face of the extrusion, between theribs thereon, on passage of the extrusion through said frame, saidsurfaces being fixed against movement normally of the plane of theextrusion during its said passage; a row of die members carried by saidframe for movement substantially normal to the plane of the extrusion inits said passage through said frame, said row being disposed transverseto the direction of said passage and each of said members having a diesurface opposed to said fixed die surfaces and engageable with the otherface of the extrusion for straightening and smoothing the latter in itssaid passage through said frame; additional die members carried by saidframe for movement substantially parallel to the direction of movementof said die members in said row, each of said additional die membershaving a die surface engageable with an edge of one of the ribs on theextrusion for straightening and smoothing the latter in its said passagethrough said frame; fluid pressure means associated with each of saiddie members for individually yieldably urging the latter against theextrusion during said passage; and means for supplying each of said fiuipressure means with fluid under pressure. f

17. The structure defined in claim 16 in which each of the fixed diesurfaces is formed on a separate die mem ber, and including meansmounting the latter on the frame for movement transverse to thedirection of movement of the extrusion in its passage through saidframe.

18. Apparatus for straightening an elongated sheetlike metal extrusionhaving on one of its faces at least one substantially straight integralstiffening rib, the combination comprising: a draw bench; a draw dieframe adapted for-passage of the extrusion therethrough and carried bysaid bench; means defining opposed die surfaces carried by said framefor straightening and smoothing engagement with the opposite faces ofthe extrusion on its said passage through said frame, means for urgingsaid die surfaces engageable with one of the faces of the extrusion,against the latter; and means mounting said frame on said bench forpivotal adjustment about an axis disposed transverse to the direction ofsaid passage, substantially parallel to the plane of the extrusion inits said passage, and between said opposed die surfaces.

References Cited in the file of this patent UNITED STATES PATENTS1,103,382 Seifert July 14, 1914 1,437,953 Baily Dec. 5, 1922 2,178,674Simons Nov. 7, 1939 2,301,960 Lermont Nov. 17, 1942 r 2,379,658 SaundersJuly 3, 1945 2,680,976 Hessenberg July 15, 1954 2,692,421 Cozzo Oct. 26,1954 2,767,767 Peterson Oct. 23, 1956 2,799,317 Toulmin July 16, 19572,872,964 Hollis Feb. 10, 1959 FOREIGN PATENTS 119,427 Great BritainOct. 3, 1918

